The Cum for Bigfoot series might not be on the road to winning a Pulitzer, but the self published ebook — a part of the widely popular “monster porn” genre — has a dedicated following that makes author Virginia Wade a net of $30,000 or more in a good month.

Wade and other authors have noticed that ebooks that have been available for more than a year are getting pulled from virtual sales for “being in violation of [Amazon’s] content guidelines,” although the publisher won’t disclose what the violation is. While some erotica is allowed, authors said that they are noticing taboo subject matter (like human/velociraptor relations) is taking a big hit.

Erotica authors have noticed that covertly changing cover art, book descriptions (which is problematic since readers then don’t know the graphic scenes in store), and titles have allowed them to put their books back on the shelves, it is taking a significant toll on sales. Emerald Ice told Business Insider that she was able to reinstate Alien Sex Slave after changing its name, but her sales have plummeted because “If I was a reader searching for hot alien sex books, I wouldn’t look twice at something called Sidney’s Alien Escapades.“